Of saline and sea lice : hydromineral challenges and osmoregulatory strategies associated with early ocean entry of juvenile pink salmon (Oncorhynchus gorbuscha) ...

• Main Author: Sackville, Michael
• Format: Text
• Language: English
• Published: University of British Columbia 2010
• Subjects: Oncorhynchus gorbuscha; Pink salmon
• Online Access: https://dx.doi.org/10.14288/1.0071106; https://doi.library.ubc.ca/10.14288/1.0071106

Pink salmon (Oncorynchus gorbuscha) enter seawater (SW) following gravel emergence at a body mass of 0.2 g. Two hydromineral challenges associated with this remarkable early ocean entry were investigated: (1) initial exposure to a hyper-osmotic environment and (2) sea louse (Lepeophtheirus salmonis) parasitism. To survive SW, pink salmon were hypothesized to develop hypo-osmoregulatory abilities as larval alevins prior to natural SW entry as post-larval fry. To test this, alevins and fry were transferred from freshwater (FW) in darkness to SW under a simulated natural photoperiod (SNP). Ionoregulatory status was assessed at 0, 1 and 5 days post-transfer. Alevins showed no evidence of hypo-osmoregulation, marked by a loss of water balance, a 35% increase in body [Cl-], and no change in gill Na⁺/K⁺-ATPase (NKA) activity. Conversely, fry maintained water balance and increased gill NKA activity by 50%. Fry gill NKA activity also increased by 50% following exposure to SNP in FW, providing the first evidence of ...